WASHINGTON - A US Senate measure encouraging states and local governments to "divest" from companies that boycott Israel has stirred controversy in Washington, with civil rights groups rallying against the proposal and Senator Bernie Sanders slamming it as "absurd".

The measure, presented in a wider Middle East foreign policy bill, was introduced last week amidst a partial shutdown of the federal government, which was caused by a political impasse over funding between Democrats and President Donald Trump's Republican Party.

"It’s absurd that the first bill during the shutdown is legislation which punishes Americans who exercise their constitutional right to engage in political activity," Sanders wrote on Twitter on Monday.

"Democrats must block consideration of any bills that don’t reopen the government. Let's get our priorities right."

That message makes a mockery of the constitutional principle that Americans are free to believe as they choose

- ACLU, on the Combating BDS Act

Newly elected Congresswoman Rashida Tlaib also criticised the proposal, which the Senate may vote on as early as Tuesday, urging politicians to remember that the US Constitution guarantees free speech.

"They forgot what country they represent. This is the US. where boycotting is a right & part of our historical fight for freedom & equality," she wrote on Twitter.

"Maybe a refresher on our U.S. Constitution is in order, then get back to opening up our government instead of taking our rights away."

The statement provoked Marco Rubio, the Republican senator who introduced the bill last week, to accuse the Palestinian-American congresswoman of anti-Semitism.

Tlaib later clarified that her comment was not aimed at Jewish-Americans, but was about Republicans' efforts to strip citizens of their right to freedom of expression instead of focusing on reopening the government.

Earlier in the day, Rubio defended the proposal, calling Sanders' statement a "lie".

He also emphasised that his proposal is legal, despite two federal court rulings in Kansas and Arizona last year concluding that it is unconstitutional to force state contractors to refrain from boycotting Israel.

'Unconstitutional'

Dozens of states have passed various forms of anti-BDS bills in recent years, but several of these measures are currently being challenged in courts across the US.

While Rubio's bill boosts local and state efforts against boycotting Israel, it also extends to boycotts of "Israeli-controlled territories", effectively targeting boycotts of Israeli businesses in the illegally occupied Palestinian West Bank and Syrian Golan Heights.

The proposal is named the "Combating BDS Act of 2019" after the Boycott, Divestment and Sanctions movement, which seeks to pressure Israel economically and politically to end its abuses against Palestinians.

"My bill doesn’t punish any political activity. It protects the right of local & state govts that decide to no longer do business with those who boycott #Israel. So boycotting #Israel is a constitutional right, but boycotting those participating in #BDS isn’t?" Rubio wrote on Twitter.

Sen. Rubio, it's clear my earlier tweet was critical of U.S. Senators like yourself, who are seeking to strip Americans of their Constitutional right to free speech. https://t.co/xFn2XeCqsZ

The American Civil Liberties Union (ACLU) responded to Rubio by explaining that the First Amendment, which grants US citizens the right to free speech, belongs to the people, not the government.

"States don't have the 'right' to punish individuals for participating in political boycotts the government doesn't agree with, which this bill encourages them to do," the group said on Twitter.

Rubio's office did not respond to MEE's request for comment on Monday.

Later in the day, the ACLU sent a letter to the members of the Senate, calling on them to reject the bill, "primarily due to First Amendment concerns".

"The Combating BDS Act sends a clear message to Americans who engage on issues of global importance that if they dare to disagree with their government, they will be penalized and placed in a lesser class with fewer opportunities," the letter said.

"That message makes a mockery of the constitutional principle that Americans are free to believe as they choose."

The Council on American Islamic Relations (CAIR) also called on its supporters to contact their elected officials and urge them to reject the bill.

"This unconstitutional bill violates the First Amendment rights of all Americans to challenge the illegal and discriminatory actions of a foreign government and goes against the principles of free speech on which our country was founded," CAIR government affairs director, Robert McCaw, said in a statement.

Government shutdown

Since late December, about 25 percent of US federal agencies have been closed because of the disagreement between Trump and Democrats over the president's demand to allocate $5bn for a border wall with Mexico.

The failure to reach an agreement has killed efforts to pass several funding bills.

In that context, Rubio's anti-BDS measure has been criticised as a distraction from the more consequential government shutdown, as well.

The timing of the bill, dubbed S1, as the first order of business of the new Senate in 2019, has even irked some politicians who are staunch supporters of Israel.

Tlaib's rise comes in defiance of decades of attacks on Palestinians in US

In a Twitter post, Senator Ben Cardin, a Democrat who introduced his own anti-BDS bill in 2017, said Senate Majority Leader Mitch McConnell should not take up any other piece of legislation that does not address the "crisis" of the shutdown.

The ACLU letter also noted the worrying nature of proposing the bill at a time when lawmakers should be trying to resolve the more pressing issue of the shutdown.

"It is particularly alarming that the Senate is considering this bill amidst a partial government shutdown," it said.

The US Campaign for Palestinian Rights provided a sample letter to its supporters, calling on them to urge their senators to vote against the proposed bill.

"I am especially outraged that while parts of the government remain shut down, the Senate would consider its most urgent act to be denying us our First Amendment rights," the letter reads.